It was a classic stage that provived thrills throughout and lots of drama as the gap on the road, and in the overall standings, between Basso and Arroyo ebbed and flowed.

The crucial moment came on the penultimate climb, the legendary and gruelling Passo del Mortirolo.

Arroyo was quickly dropped by the contenders as Liquigas turned on the gas.

Sastre and Vinokourov were next to be dropped off the back before Evans too failed to keep the pace by now being set by Basso himself.

Only Nibali and Scarponi could stay with him and when they caught and passed Stefano Garzelli, who had broken away on the previous climb, they were at the front and riding for time.

They went over the top with a 55sec lead over Vino, who had broken free of his companions, with Evans 1:30 back and Arroyo at 1:42.

Arroyo put in a breathtaking descent, though, and by the bottom he had joined Vinokourov and cut the lead to just 38secs, boosting his chances of holding onto pink as he started the day 2:27 ahead of Basso.

Evans had managed to get back up to Sastre and Frenchman John Gadret and when the three joined Vino and Arroyo, they appeared to have the group needed to reel in the three leaders.

However, only Arroyo and Evans seemed willing to work with Sastre occasionally pulling a turn.

Up front Basso and Nibali were going hell for leather with Scarponi putting in some work as they reached the closing stages.

The two Liquigas riders were far better organised than the chasers and suddenly, over the last 12 kilometers or so, the gap started to increase quickly.

It was heart-breaking for Arroyo, whose grit and determination to climb back after looking dead and buried at the bottom of the Mortirolo was a wonder to witness.

But by the time he reached the line, losing 3:06 as well as Basso's 12 bonus seconds for finishing second, he looked a beaten man.

Evans said the Liquigas team was the difference. "There's five of them and there's one of me and the rest of us are all left as the best of each of our team," he said. "They've got the strength in the numbers and also the strength of their leader. Ivan has been consistent and a little bit better than me in the second half of the Giro. I'm not at the same level as I was at the start. But there's still another day tomorrow so we'll see."

"It was a very difficult stage. It was fast from the start and we spent a lot of energy ahead of tomorrow's stage. I didn't have bad legs, but aches and pains I've had are disappearing, but there are a few riders who are going better than me," Sastre commented after stage 19. "We have to congratulate Liquigas, who did sensational work and who put their two leaders on the podium today."

"Behind, there wasn't the necessary understanding or strength to reduce the differences," Sastre added and concluded "At least we tried to save the day and I am content to be able to arrive with this group behind the three strongest men of the race."

With a mountain stage to come on Saturday and Sunday's short time trial, only a disaster looks capable of denying Basso a second Giro d'Italia crown.